Computer telephony integration (CTI) is a term used to describe a general architecture in which functions traditionally provided by a telephone switching system are provided to some degree by personal computers and/or computer servers which are not dedicated to switching and telephony applications alone. CTI provides means for efficiently providing human machine interfaces (HMIs) to telephone users, and thus which can provide new and enhanced features and more ease of use for new and enhanced features than in the past.
CTI has been provided by two well known and basic architectures referred to as first party call control. As shown simply in FIG. 1, first party call control involves interfacing a personal computer 1 between a telephone set 3 and a telephone switching system. The telephone set 3 is connected to the switching system 5 via the computer 1. A significant benefit of this scheme is that the computer is in control of the telephone at all times, and can provide an excellent and seamless HMI.
For example, the computer may be programmed to set up a regular conference at 4:00 pm. Not noticing the time, a user may try to make a call using the telephone in the usual manner. Because the telephone is connected to the computer, the computer program could display a warning, and could present the alternatives of postponing the conference call or postponing the new call.
In some cases the electronic portions of the telephone are to some degree implemented within the chassis of the computer, and only the handset or headset of the telephone is attached outside the computer.
Unfortunately, the computer may lose power, or more commonly, crash (freeze). In either case, voice telephony is likely to be lost. In addition, in the event the computer is being serviced, voice telephone service is unavailable to the user.
Many computer users have switched from use of a desktop computer to use of a laptop or notepad computer. Such machines have very limited expansion capacity, and thus are difficult to design to handle first party call control. In addition, such computers are often stored, and are not available for telephony use.
FIG. 2 illustrates an architecture of another system for implementing first party call control. In this case the telephone is connected directly to the switching system. The computer is connected to the telephone line in a manner similar to an extension telephone.
While in first party call control as shown in FIG. 2 voice communication is essentially as reliable as if no computer had been used, this architecture has the disadvantage that seamless operation cannot be provided, and the HMI is very poor. Relating to the operation example given above, the user would be presented with a confusing situation, since by the time that the computer would present a display of the call progress alternatives, the telephone would already have seized a line circuit in the switching system, and the possibility of remotely setting up the conference call would be blocked.
The form of call control involving use of a personal computer to provide an enhanced HMI and enhanced services in telephony thus provides a significant dilemma, since personal computers have a reputation with some users as being unreliable. It is believed that voice service is seen by most people as being the single most critical form of communication in a multimedia environment; users may be prepared to lose a data connection for a period of time, but will not accept the loss of voice communications. As noted above, the first method of first party call control described above cuts off voice communications in the event of computer failure, while the second method provides a poor HMI and very limited call control capability.